I wouldn’t of thought it was a thieving toerag they would have stolen the bike and left the chainring bolts, seriously I’ve never had the bolts come loose what type of bike is it how old is it and what type riding do you do
I have had 4 out of 5 chainring bolts come loose (chainrings fitted myself) - and realised this 100km in to a 200+km cycle. Quite difficult to tighten with the tools I had. As well as my hex key I needed a wide bladed screwdriver - I managed to borrow a crowbar which allowed me to tighten them sufficiently to complete the ride.
So I suggest that the OP's bolts have just sequentially come loose and fallen out.
If a rider looks down at their chainset (eg after a shift), if one of the chainrings is 'meandering', stop and check the bolts DAMHIKT.
Remedial action: Procure set of 5 bolts; remove and clean chainrings and cranks; refit rings using medium locktite on the bolt threads.